Question

我有以下n条记录：

###Date Rank1 Rank2 Rank3 Rank4 Rank5 Rank6 Rank7  
10-01-2015    1    0    0    0    0    0    0   
10-01-2015    0    1    0    0    0    0    0   
10-01-2015    0    0    1    0    0    0    0   
10-01-2015    0    0    0    1    0    0    0   
10-01-2015    0    0    0    0    1    0    0   
10-01-2015    0    0    0    0    0    1    0   
10-01-2015    0    0    0    0    0    0    1

我想要的输出是

### Date Rank1 Rank2 Rank3 Rank4 Rank5 Rank6 Rank7  
  10-01-2015    1    1    1    1    1    1    1

有没有办法实现这个目标？

Answer 1

您需要sum()和group by

select
Date,
sum(Rank1) as Rank1,
sum(Rank2) as Rank2,
sum(Rank3) as Rank3,
sum(Rank4) as Rank4,
sum(Rank5) as Rank5,
sum(Rank6) as Rank6,
sum(Rank7) as Rank7
from table_name
group by Date

Answer 2

SELECT Date, sum(Rank1), sum(Rank2), 
             sum(Rank3), sum(Rank4), 
             sum(Rank5), sum(Rank6), 
             sum(Rank7)

FROM YourTable

GROUP BY Date

可以用于上面的例子，但是如果那里有2，你想要什么？毕竟，排名通常从1开始，而不是零。通过将sum（）替换为min（）来选择每天的峰值等级是微不足道的。

将n条记录合并到MySQL中的单条记录中

2 个答案: